/*
 
 File: URLCacheConnection.m
 Abstract: The NSURL connection class for the URLCache sample.
 
 Version: 1.0
 
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 */

#import "URLCacheConnection.h"

@interface URLCacheConnection (Private)

- (void) connection: (NSURLConnection*) connection didNotStart: (NSError *) error;

@end


@implementation URLCacheConnection

@synthesize delegate;
@synthesize receivedData;
@synthesize lastModified;
@synthesize theRequest;
@synthesize theResponse;

/* This method initiates the load request. The connection is asynchronous, 
 and we implement a set of delegate methods that act as callbacks during 
 the load. */

- (id) initWithURL:(NSURL *)theURL delegate:(id<URLCacheConnectionDelegate>)theDelegate
{
    if (self = [super init]) {
		
        self.delegate = theDelegate;
		
        /* Create the request. This application does not use a NSURLCache 
         disk or memory cache, so our cache policy is to satisfy the request
         by loading the data from its source. */
        
        self.theRequest = [NSMutableURLRequest requestWithURL:theURL
                                                    cachePolicy:NSURLRequestReloadIgnoringLocalCacheData 
                                                timeoutInterval:60];
		
        /* create the NSMutableData instance that will hold the received data */
        receivedData = [[NSMutableData alloc] initWithLength:0];
		
        /* Create the connection with the request and start loading the
         data. The connection object is owned both by the creator and the
         loading system. */
		
        NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:theRequest 
                                                                      delegate:self 
                                                              startImmediately:YES];
        if (connection == nil) {			
          [self connection: connection didNotStart: nil];
        }
    }
	
    return self;
}


- (void)dealloc
{
	[theRequest release];
	[theResponse release];
  [receivedData release];
  [lastModified release];
  [super dealloc];
}


#pragma mark NSURLConnection delegate methods

- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    /* This method is called when the server has determined that it has
     enough information to create the NSURLResponse. It can be called
     multiple times, for example in the case of a redirect, so each time
     we reset the data. */
    
    [self.receivedData setLength:0];

    /* Try to retrieve last modified date from HTTP header. If found, format  
     date so it matches format of cached image file modification date. */
    if ([response isKindOfClass:[NSHTTPURLResponse self]]) {
		
		self.theResponse = (NSHTTPURLResponse *)response;
		
        NSDictionary *headers = [(NSHTTPURLResponse *)response allHeaderFields];
		
        NSString *modified = [headers objectForKey:@"Last-Modified"];
        if (modified) {
            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
            [dateFormatter setDateFormat:@"EEE, dd MMM yyyy HH:mm:ss zzz"];
            self.lastModified = [dateFormatter dateFromString:modified];
            [dateFormatter release];
        }
        else {
            /* default if last modified date doesn't exist (not an error) */
            self.lastModified = [NSDate dateWithTimeIntervalSinceReferenceDate:0];
        }
    }
}

- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    /* Append the new data to the received data. */
    [self.receivedData appendData:data];
}


- (void) connection: (NSURLConnection*) connection didNotStart: (NSError *) error
{
	[self.delegate connectionDidNotStart: self];
	[connection release];
}

- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    [self.delegate connectionDidFail:self];
    [connection release];
}


- (NSCachedURLResponse *) connection:(NSURLConnection *)connection 
                   willCacheResponse:(NSCachedURLResponse *)cachedResponse
{
    /* this application does not use a NSURLCache disk or memory cache */
    return nil;
}


- (void) connectionDidFinishLoading:(NSURLConnection *)connection
{
    [self.delegate connectionDidFinish:self];
    [connection release];
}


@end